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Flavonoids of some Asclepiadaceous plants
Phytochemistry, 1968, Vol. 7, pp. 1703 to 1704.
Pergamon Press.
Printed in England
SHORT COMMUNICATION
FLAVONOIDS
OF SOME ASCLEPIADACEOUS
S. SANKARA SUBRAMANIAN and A. G. R. Department
of Chemistry, Jawaharlal Institute of Postgraduate Pondicherry-6, India
PLANTS
NAIR
Medical Education and Research,
(Received 24 April 1968) Abstract-The distribution of flavonoid glycosides in some South Indian plants belonging to the Asclepiadaceae has been studied and is found to be significantly in favour of quercetin; kaempferol is present in traces only and flavone was absent from all of the plants examined. Rutin has been isolated from the leaves of Hemidesmus indicus and from the pericarp of the follicles of Leptadenia reticulata in significant amounts. The seeds of L. reticulata are rich in hyperoside. IN RECENT years, a number of investigators have been interested in the study of comparative biochemistry of flavonoids, and the distribution pattern of these pigments in certain plant orders has been considered to have some chemotaxonomical value.* Little work has been recorded2 on the flavonoid glycosides of plants belonging to the family Asclepiadaceae, though kaempferol and quercetin are known3 to occur in some members of this family. In continuation of our earlier work4 on the survey of flavonoids in South Indian plants and in view of the fact that a number of plants of this family are valued in the Indian indigenous system of medicine,5 we have systematically examined different parts of some Asclepiadaceae plants which are commonly found in South India. 6 Our results are summarized in Table 1. Leptadenia reticulata does not produce any milky latex in the stems or leaves, but fresh follicles, on plucking or cutting with a sharp blade, yield a thick yellow latex which coagulates in a few minutes. This observation of ours prompted us to study the pigment of the latex as well as the pericarp and the seeds. Another interesting observation made by us relates to the occurrence of brownish-yellow pubiscent hairs on the follicles (especially the immature ones) of Marsdenia volubilis. Hemidesmus indicus known as Indian Sarasaparilla is reputed for its diuretic value; the leaves of this plant do not seem to have been examined earlier. EXPERIMENTAL The following procedure, in brief, was adopted for the identification of flavonoids in the plant material; in the case of Marsdenia volubilis, the entire follicles were extracted by cold maceration with methanol, when the hairs got dislodged and the pigment was easily extracted. Fresh plant material was extracted with cold methanol by repeated mincing in a Waring blender till the last extract had practically no yellow colour. The f E. C. BATE-SMITH,in Chemical PIant Taxonomy (edited by T. SWAIN), p. 127, Academic Press, London (1963). 2 J. B. HARBORNE,Comparative Biochemistry of the Flavonoids, p. 209, Academic Press, London (1967). 3 E. C. BATE-SMI~~~, J. Linn. Sot. (Botany) 58,39 (1962). 4 S. SANKARASUBRAMANIAN and A. G. R. NAIR, Indian J. Chem. 1,450 (1963). 5 K. R. KIRTIKAR and B. D. BASU, Indian Medicinal Plants, Vol. 3, pp. 1596-1635. Lalit Mohan Basu, India (1933). 6 J. S. GAMBLE, Flora of the Presidency of Madras, Vol. 2, pp. 578-598. Botanical Survey of India, Calcutta (1957). 1703
S. SANKARASUBRAMANIAN~~~
1704
A.G.R.NAIR
TABLET. FLAVONOLGLYCOSIDESOFTHEASCLEPIADACEAE
Parts examined
Plant species W. & A.
Leptadenia
reticulata
Marsdenia
volubilis T. Cook
Hemidesrnus
indicus R. Br.
Latex Follicle, pericarp Seeds Follicle, hairs (Rich in free quercetin) Stem and leaves7 Flowers Leaves
Calotropisgigantea
R. Br.
Telosma minor Craib Daemia extensa R. Br. (Pergularia extensa N.E. Br.) Heterostemma tanjorense W. & A.
Flowers Seeds Flowers Stem Stem Follicle, pericarp
* Indicates isolation of the glycosides. t Indicates the pigment in traces. $ Hyperoside = quercetin 3-galactoside ; rutin=quercetin cetin 3-glucoside.
Flavonol glycosides identified1
Aglycones after hydrolysis (total ethyl acetate extract)
Hyperoside Isoquercitrin Rutin* Hyperoside* Hyperoside* Rutin
Quercetin Kaempferoli
Kaempferol Glycoside Hyperoside Isoquercitrin Rutin Hyperoside Rutin* Hyperoside Rutin Hyperoside Hyperoside Isoquercitrin Hyperoside
Kaempferol
Rutin
3-rhamnosylglucoside;
Quercetin
Quercetin Quercetin Quercetin Kaempferolt Quercetin Quercetin Quercetin Kaempferolt Quercetin
isoquercitrin=quer-
combined extracts were concentrated in vacua till all the organic solvent was removed. The aqueous concentrate was repeatedly shaken with petrol. ether, 60-80”, ether and ethyl acetate in succession. The residues from the ether and ethyl acetate layers were studied by paper chromatography in five solvent systems, and the colour of spots on the chromatogram observed by exposure to ammonia and under U.V. light. In cases where a fair concentration of glycoside was indicated in the ethyl acetate extract, the concentrate was taken into the minimum amount of aqueous alcohol, layered with ether and left in an ice-chest for about a week, when there was separation of the major glycosidic pigment. The isolated glycoside in each case was fully characterized by colour reactions, spectral properties, R, values, including co-chromatography, and mixed m.p. with authentic samples, as well as hydrolysis by 7 per cent H$04 in aqu. EtOH to yield the flavonol (quercetin) and sugars which were characterized by paper chromatography and comparison with authentic samples. In cases where the proportion of the flavonol glycosides in the ethyl acetate concentrate was low, they were separated by preparative paper chromatography (Whatman No. 3, n-butanol:27 per cent acetic acid, 1: 1) and the zones developed eluted with methanol. The properties (colour reactions, R, in PC and TLC) of the eluted pigments were compared with those of authentic samples of the compounds. Acknowledgements-We are grateful to Professor Hiirhammer, University of Munich, for an authentic sample of hyperoside and Dr. S. B. Rao, Navaratna Pharmaceutical Laboratories, Cochin, for an authentic sample of rutin. The authentic sample of isoquercitrin was earlier isolated by us from the flowers of Opuntia dillenii.8 Our thanks are due to Principal, Dr. D. J. Reddy, for encouragement and Mr. B. Kannabiran, M.Sc., of our institute for the collection and identification of the plants.
7 D. VENKATARAO, E. VENKATA RAO and V. VISWANATHAM,Current Sci. (Zndia) 36, 421 (1967). 8 A. G. R. NAIR and S. SANKARA SUBRAMANIAN, Current Sci. (Zndia) 33, 211 (1964).
Pergamon Press.
Printed in England
SHORT COMMUNICATION
FLAVONOIDS
OF SOME ASCLEPIADACEOUS
S. SANKARA SUBRAMANIAN and A. G. R. Department
of Chemistry, Jawaharlal Institute of Postgraduate Pondicherry-6, India
PLANTS
NAIR
Medical Education and Research,
(Received 24 April 1968) Abstract-The distribution of flavonoid glycosides in some South Indian plants belonging to the Asclepiadaceae has been studied and is found to be significantly in favour of quercetin; kaempferol is present in traces only and flavone was absent from all of the plants examined. Rutin has been isolated from the leaves of Hemidesmus indicus and from the pericarp of the follicles of Leptadenia reticulata in significant amounts. The seeds of L. reticulata are rich in hyperoside. IN RECENT years, a number of investigators have been interested in the study of comparative biochemistry of flavonoids, and the distribution pattern of these pigments in certain plant orders has been considered to have some chemotaxonomical value.* Little work has been recorded2 on the flavonoid glycosides of plants belonging to the family Asclepiadaceae, though kaempferol and quercetin are known3 to occur in some members of this family. In continuation of our earlier work4 on the survey of flavonoids in South Indian plants and in view of the fact that a number of plants of this family are valued in the Indian indigenous system of medicine,5 we have systematically examined different parts of some Asclepiadaceae plants which are commonly found in South India. 6 Our results are summarized in Table 1. Leptadenia reticulata does not produce any milky latex in the stems or leaves, but fresh follicles, on plucking or cutting with a sharp blade, yield a thick yellow latex which coagulates in a few minutes. This observation of ours prompted us to study the pigment of the latex as well as the pericarp and the seeds. Another interesting observation made by us relates to the occurrence of brownish-yellow pubiscent hairs on the follicles (especially the immature ones) of Marsdenia volubilis. Hemidesmus indicus known as Indian Sarasaparilla is reputed for its diuretic value; the leaves of this plant do not seem to have been examined earlier. EXPERIMENTAL The following procedure, in brief, was adopted for the identification of flavonoids in the plant material; in the case of Marsdenia volubilis, the entire follicles were extracted by cold maceration with methanol, when the hairs got dislodged and the pigment was easily extracted. Fresh plant material was extracted with cold methanol by repeated mincing in a Waring blender till the last extract had practically no yellow colour. The f E. C. BATE-SMITH,in Chemical PIant Taxonomy (edited by T. SWAIN), p. 127, Academic Press, London (1963). 2 J. B. HARBORNE,Comparative Biochemistry of the Flavonoids, p. 209, Academic Press, London (1967). 3 E. C. BATE-SMI~~~, J. Linn. Sot. (Botany) 58,39 (1962). 4 S. SANKARASUBRAMANIAN and A. G. R. NAIR, Indian J. Chem. 1,450 (1963). 5 K. R. KIRTIKAR and B. D. BASU, Indian Medicinal Plants, Vol. 3, pp. 1596-1635. Lalit Mohan Basu, India (1933). 6 J. S. GAMBLE, Flora of the Presidency of Madras, Vol. 2, pp. 578-598. Botanical Survey of India, Calcutta (1957). 1703
S. SANKARASUBRAMANIAN~~~
1704
A.G.R.NAIR
TABLET. FLAVONOLGLYCOSIDESOFTHEASCLEPIADACEAE
Parts examined
Plant species W. & A.
Leptadenia
reticulata
Marsdenia
volubilis T. Cook
Hemidesrnus
indicus R. Br.
Latex Follicle, pericarp Seeds Follicle, hairs (Rich in free quercetin) Stem and leaves7 Flowers Leaves
Calotropisgigantea
R. Br.
Telosma minor Craib Daemia extensa R. Br. (Pergularia extensa N.E. Br.) Heterostemma tanjorense W. & A.
Flowers Seeds Flowers Stem Stem Follicle, pericarp
* Indicates isolation of the glycosides. t Indicates the pigment in traces. $ Hyperoside = quercetin 3-galactoside ; rutin=quercetin cetin 3-glucoside.
Flavonol glycosides identified1
Aglycones after hydrolysis (total ethyl acetate extract)
Hyperoside Isoquercitrin Rutin* Hyperoside* Hyperoside* Rutin
Quercetin Kaempferoli
Kaempferol Glycoside Hyperoside Isoquercitrin Rutin Hyperoside Rutin* Hyperoside Rutin Hyperoside Hyperoside Isoquercitrin Hyperoside
Kaempferol
Rutin
3-rhamnosylglucoside;
Quercetin
Quercetin Quercetin Quercetin Kaempferolt Quercetin Quercetin Quercetin Kaempferolt Quercetin
isoquercitrin=quer-
combined extracts were concentrated in vacua till all the organic solvent was removed. The aqueous concentrate was repeatedly shaken with petrol. ether, 60-80”, ether and ethyl acetate in succession. The residues from the ether and ethyl acetate layers were studied by paper chromatography in five solvent systems, and the colour of spots on the chromatogram observed by exposure to ammonia and under U.V. light. In cases where a fair concentration of glycoside was indicated in the ethyl acetate extract, the concentrate was taken into the minimum amount of aqueous alcohol, layered with ether and left in an ice-chest for about a week, when there was separation of the major glycosidic pigment. The isolated glycoside in each case was fully characterized by colour reactions, spectral properties, R, values, including co-chromatography, and mixed m.p. with authentic samples, as well as hydrolysis by 7 per cent H$04 in aqu. EtOH to yield the flavonol (quercetin) and sugars which were characterized by paper chromatography and comparison with authentic samples. In cases where the proportion of the flavonol glycosides in the ethyl acetate concentrate was low, they were separated by preparative paper chromatography (Whatman No. 3, n-butanol:27 per cent acetic acid, 1: 1) and the zones developed eluted with methanol. The properties (colour reactions, R, in PC and TLC) of the eluted pigments were compared with those of authentic samples of the compounds. Acknowledgements-We are grateful to Professor Hiirhammer, University of Munich, for an authentic sample of hyperoside and Dr. S. B. Rao, Navaratna Pharmaceutical Laboratories, Cochin, for an authentic sample of rutin. The authentic sample of isoquercitrin was earlier isolated by us from the flowers of Opuntia dillenii.8 Our thanks are due to Principal, Dr. D. J. Reddy, for encouragement and Mr. B. Kannabiran, M.Sc., of our institute for the collection and identification of the plants.
7 D. VENKATARAO, E. VENKATA RAO and V. VISWANATHAM,Current Sci. (Zndia) 36, 421 (1967). 8 A. G. R. NAIR and S. SANKARA SUBRAMANIAN, Current Sci. (Zndia) 33, 211 (1964).